GE 90-30 Plastic cases

[Corsair]

Just looking for comments here - does anybody else seem to have above-average problems with cracked plastic on old 90-30 equipment?

We had a 364 CPU where the the case was so brittle that it shattered. Some of the I/O module retaining stuff breaks pretty easily.

I guess the problem is not unique to GE. We just ran a service call on some 30 year plus old Symax that seemed to break everything that was touched on the I/O module wiring arms. I don't remember them being that fragile when they were installed.

Power supply capacitor aging seems to be related to intermittent shutdowns and memory scrambles in older stuff.

Even wire has a finite usable lifetime.

There appear to be more reasons to change out really old stuff besides hardware and software obsolescence. We've got a Symax install with close to 40 years on several UV Prom CPUs but the customer hasn't got the budget to change. They manage to solder triacs into the output cards and keep going.

It really hurts when you keep telling them that they need to change the stuff and when the inevitable emergency comes they do it with someone else.

 

[Steve Bailey]

I have noticed that in general, plastic gets brittle with age. Heat probably has an impact as well. And it's not limited to GE.
Sometimes it's harder to get a PLC upgrade included in your budget than to get approval for a brand new machine. The new machine will almost certainly come out of the capital budget, while the bean counters may try to push the controls upgrade into the maintenance budget.